Many consider wall-to-wall carpeting to be the peak of luxury; housewives love it for the warm atmosphere it brings, businessmen value it for the air of corporate dignity it lends their offices; but to those who must clean and maintain it, wall-to-wall carpeting is an immense headache. It must be cleaned in place; the cleaning must be accomplished in a relatively short time and if the carpet is not kept scrupulously clean, its life may be severely shortened. For these reasons, the carpet cleaning industry is constantly seeking improved methods and machinery for cleaning carpets.
Recently, a radically new approach to cleaning carpets has been developed which uses a powdered cleaning composition containing a mixture of extremely porous solid particles and a solvent. This new cleaning composition is described in U.S. Pat. No. 4,013,594 and has proved especially effective in removing soil from carpets. Further, only a short interval is required between application and removal of the powdered cleaning composition. Using this new cleaning composition, it has now become possible to clean wall-to-wall carpets in offices and stores during working hours with little disruption of normal affairs. However, this progress in cleaning compositions has exposed shortcomings in the carpet cleaning machines known to the prior art.
When the devices which are known to the prior art are used with this new powdered cleaning composition, it is found that some areas of the carpet are cleaned much better than other areas and that a streaked appearance results. It is theorized that this streaked appearance is due to the fact that the powder, unlike a liquid, must be physically moved into intimate contact with the fibers to be cleaned. Therefore, to obtain the full benefit of the powdered cleaning composition, it is thought to be desirable to provide a device which is capable of transmitting a great deal of energy to the carpet in order to bring the powdered cleaning composition into intimate contact with the fiber while distributing this energy uniformly over the area which is scrubbed.
It has been discovered that these objectives can be accomplished by providing a device which has two angularly oscillating scrubbers which scrub overlapping areas of the carpet but do not collide. The scrubbers impart a back and forth motion to the fibers and it is thought that this motion enables the particles to quickly work their way into intimate contact with the fibers and thus clean them.